Kids are clever, they follow what you do, hence if possible, stop slapping him.
Uses words of love to melt him. Say 1 whole long logical and sad feeling that you have to him, they understand, talk as long as you can, and be serious and sad, they can feel it. (Anyway it's only work for 1st time only. )
I always tell my girl, whenever she see any kids, friend friend, whenever she see any kid, so she will not be very bad or what to them. now she see other kid will say friend friend.
Try again slowly to get him open up, we start since young too. At times my girl is sensitive and get angry when people walk pass her and knock into her, i will tell her it's ok, they are not purposely, say sorry behalf or stranger. As we told her to say sorry when she do wrong also.
Read more